如下,__age為私有屬性：
class Foo(object):
def __init__(self):
self.name = '0bug'
self.__age = 20
self._position = 'programmer'
def get_age(self):
return self.__age
f = Foo()
print(f.name) # 0bug
print(f._position) # programmer
print(f.__age) # AttributeError: 'Foo' object has no attribute '__age'
print(f._Foo__age) # 20
print(f.get_age()) # 20
